Authorities say five people have been taken to the hospital in critical condition after being exposed to carbon monoxide at a Sioux City extended-stay motel.

The Sioux City Journal reports a 30-year-old woman, her two children and her parents were transported to UnityPoint Health-St. Luke's for treatment of carbon monoxide poisoning Wednesday.

According to Sioux City Fire Rescue Assistant Chief Dan Cougill, someone reported around 8 p.m. that five people occupying a unit at the Corey Motel were vomiting and experiencing headaches. First responders found them and said they showed signs of carbon monoxide exposure.

Cougill said all five, whose identities have not been released, are expected to make full recoveries.

Officials say the motel's units are separate and other units were not affected. The source of the carbon monoxide is under investigation.